Yanhui Wang1,2,3, Zujiao Chen1,2, Jing Li1,2, Zhen Li4, Jianteng Xie2,5, Duan Wang4, Sheng Li2,5, Yifan Zhang1,2, Tiantian Liang1,2, Hokhim Yau1,2, Chunfang Qi2,5, Qiuling Li6, Shaochun Lin6, Shaogui Zhang1,2, Wenjian Wang7,8,9,10. 1. The Second School of Clinical Medicine, Southern Medical University, Guangzhou, 510515, China. 2. Division of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, 106 Zhongshan Er Road, Main Building, Room 1436, 510080, GD, China. 3. Division of Nephrology, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325000, China. 4. Division of Clinical Nutrition, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, 510080, China. 5. School of Medicine, South China University of Technology, Guangzhou, 510006, China. 6. Shantou University Medical College, Shantou, 515041, China. 7. The Second School of Clinical Medicine, Southern Medical University, Guangzhou, 510515, China. wwjph@126.com. 8. Division of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, 106 Zhongshan Er Road, Main Building, Room 1436, 510080, GD, China. wwjph@126.com. 9. School of Medicine, South China University of Technology, Guangzhou, 510006, China. wwjph@126.com. 10. Shantou University Medical College, Shantou, 515041, China. wwjph@126.com.
Abstract
PURPOSE: The aim of this research was to develop a simple equation to evaluate dietary protein intake (DPI) in patients with stage 3 chronic kidney disease (CKD) using the blood urea nitrogen (BUN)/serum creatinine (SCr) ratio (BUN/SCr). METHODS: In a prospective cohort of 136 inpatients with stage 3 CKD from 2 centres, the estimated dietary protein intake (DPI) was calculated using Maroni's formula after the patients implemented a 7 day protein-restricted diet. We developed estimation equations based on BUN/SCr and the spot urinary urea nitrogen (UUN)/urinary creatinine (UCr) ratio (UUN/UCr) in combination with sex and body mass index (BMI). These equations were then internally and externally validated. RESULTS: The following candidate parameters were derived from univariate regression analysis for 5 established models: sex, BMI, BUN/SCr, UUN and UUN/UCr. Sex and BMI were included in all models after variable evaluation using multiple regression analysis. UUN, UUN/UCr and BUN/SCr were included in model 3, model 4 and model 5, respectively. Both internal and external validation indicated that model 5 resulted in the lowest values for bias and root mean square error and the highest P30 compared with model 3 and model 4. Therefore, the model 5 equation, DPI = - 5.18 (- 14.49 if the patient is female) + 1.89 × BMI + 1.38 × BUN/SCr, was selected because of the higher correlation (r = 0.498) between the estimated DPI and predicted DPI. CONCLUSION: The DPI equation developed using BUN/SCr, sex and BMI may be used to estimate protein intake for patients with stage 3 CKD. TRIAL REGISTRATION: Chinese Clinical Trial Registry Center (ChiCTR-ROC-17011363). Registered on 11 May 2017, Retrospectively registered, http://www.chictr.org.cn/index.aspx .
PURPOSE: The aim of this research was to develop a simple equation to evaluate dietary protein intake (DPI) in patients with stage 3 chronic kidney disease (CKD) using the blood urea nitrogen (BUN)/serum creatinine (SCr) ratio (BUN/SCr). METHODS: In a prospective cohort of 136 inpatients with stage 3 CKD from 2 centres, the estimated dietary protein intake (DPI) was calculated using Maroni's formula after the patients implemented a 7 day protein-restricted diet. We developed estimation equations based on BUN/SCr and the spot urinary urea nitrogen (UUN)/urinary creatinine (UCr) ratio (UUN/UCr) in combination with sex and body mass index (BMI). These equations were then internally and externally validated. RESULTS: The following candidate parameters were derived from univariate regression analysis for 5 established models: sex, BMI, BUN/SCr, UUN and UUN/UCr. Sex and BMI were included in all models after variable evaluation using multiple regression analysis. UUN, UUN/UCr and BUN/SCr were included in model 3, model 4 and model 5, respectively. Both internal and external validation indicated that model 5 resulted in the lowest values for bias and root mean square error and the highest P30 compared with model 3 and model 4. Therefore, the model 5 equation, DPI = - 5.18 (- 14.49 if the patient is female) + 1.89 × BMI + 1.38 × BUN/SCr, was selected because of the higher correlation (r = 0.498) between the estimated DPI and predicted DPI. CONCLUSION: The DPI equation developed using BUN/SCr, sex and BMI may be used to estimate protein intake for patients with stage 3 CKD. TRIAL REGISTRATION: Chinese Clinical Trial Registry Center (ChiCTR-ROC-17011363). Registered on 11 May 2017, Retrospectively registered, http://www.chictr.org.cn/index.aspx .